There is an increasing demand on next generation infrared imagers to bring enhanced functionality to pixels. Such functionality could include control over the color, polarization, and dynamic range of the sensor, and could lead to the development of an infrared retina, and to enable other applications. An infrared retina is defined as an infrared focal plane array (IR-FPA) that works similarly to the human eye to receive different spectral responses (colors) on different spatial pixels, like rods and cones, but without the limitation of a fixed spectral response per pixel.
These developments at the sensor-level demands advanced spatio-temporal circuitry at the pixel level. One approach to realize an infrared retina involves the use of spectrally adaptive sensors that are bias tunable by exploiting the quantum confined Stark effect (QCSE) in the quantum dots in a well (DWELL) heterostructure. Combined with a projection algorithm, the QCSE can obtain a continuously tunable detector with overlapping wavelengths bands that can be used for target recognition. Only one focal plane array (FPA) may be used to realize multicolor images, reducing the prerequisite of different spectral bands sensors and the number of connections on same pixel. However, while commercially available ROICs offer a two-color, or dual-band, capability for quantum well infrared photodetectors (QWIP), they are based on dual stacked sensors, which require at least two contacts to the FPA. Moreover, the global pixel biasing in conventional ROICs does not allow advanced processing at the pixel level.
Accordingly, what is needed is an ROIC that provides a wide voltage range bias and the ability to independently control the voltage bias and its respective polarity on each pixel.